Scanner devices, such as flatbed scanners, are well-known in the art and produce machine-readable image data signals that are representative of a scanned object, such as a photograph or a page of printed text. In a typical scanner application, the image data signals produced by the scanner may be used by a personal computer to reproduce an image of the scanned object on a suitable display device, such as a CRT or a printer.
A typical flatbed scanner may include illumination and optical systems to accomplish scanning of the object. The illumination system illuminates a portion of the object (commonly referred to as a “scan region”), whereas the optical system collects light reflected by the illuminated scan region and focuses a small area of the illuminated scan region (commonly referred to as a “scan line”) onto the surface of a photosensitive detector positioned within the scanner. Image data representative of the entire object then may be obtained by sweeping the scan line across the entire object, usually by moving the illumination and optical systems with respect to the object.
By way of example, the illumination system may include a light source (e.g., a fluorescent or incandescent lamp or an array of light emitting diodes (LEDs)). The optical system may include a lens and/or mirror assembly to focus the image of the illuminated scan line onto the surface of the detector. Alternatively, a so-called “contact image sensor” (CIS) may be used to collect and focus light from the illuminated scan region onto the detector.
The photosensitive detector used to detect the image light focused thereon by the optical system may comprise a charge-coupled device (CCD), although other devices may be used. A typical CCD may comprise an array of individual cells or “pixels,” each of which collects or builds-up an electrical charge in response to exposure to light. Since the quantity of the accumulated electrical charge in any given cell or pixel is related to the intensity and duration of the light exposure, a CCD may be used to detect light and dark spots on an image focused thereon.
While scanner devices of the type described above are known and are widely used, it is often desirable to scan transparent images, such as slides or negatives. Unfortunately, however, such reflective type scanner devices are not well-suited for scanning transparent images, such as slides or negatives, since they are designed to detect light that is reflected by the image to be scanned. Accordingly, if such a reflective type scanner is to be used to scan transparent images, some means of directing light through the image must be provided. The transmitted light is then detected by the image sensor of the scanner and processed in a conventional manner.
One such device that allows reflective type scanners to scan transparent images is described in U.S. Pat. No. 5,463,217 issued to Sobol et al., and entitled “Adapter for Scanning Transparencies with a Reflective Document Scanner” which is hereby incorporated herein by reference for all that it discloses. Sobol et al. describe a completely passive adapter for scanning transparent images with a reflective scanner without requiring a separate light source for back lighting the transparent image. Instead, the adapter utilizes one or more mirrors to capture and re-direct through the transparent image light produced by the scanner light source. While the adapter works well and eliminates the need to provide a separate light source, the user must manually place the transparent image within the adapter before the transparent image can be scanned. If the user desires to scan a plurality of such transparent images, he or she first must place each individual transparent image within the adapter, then actuate the scanner in order to scan the image. While this procedure is effective from a functional standpoint, it is relatively time-consuming, cumbersome, and carries an increased risk that the transparent image may become damaged due to the excessive handling involved.